Mattress



FIG. 1 is a front/top perspective view of a mattress showing one embodiment of the new design;

FIG. 2 is a front/top perspective view a mattress showing another embodiment of the new design;

FIG. 3 is a front/top perspective view a mattress showing another embodiment of the new design;

FIG. 4 is a front/top perspective view a mattress showing another embodiment of the new design; and,

FIG. 5 is a top plan view a mattress showing the embodiment of FIG. 1.

In the drawings, the broken lines illustrate environment and form no part of the claimed design. 

CLAIM The ornamental design for a mattress, substantially as shown and described. 